TRANSACTIONS OF WAGNER 

 644 



TERTIARY FAUNA OF FLORIDA 



This shell should not, in my opinion, be united with A. plicahira, as has 

 been done by Heilprin. When properly discriminated it is a smaller and 

 more rhombical shell, with lower and more anterior beaks, and more produced 

 and pomted posterior end ; the base and hinge-line are nearly parallel, and 

 the latter is narrower in specimens of the same size than in A. plicatiira. 

 Both have about thirty-five ribs, but in A. hnprocera these are plain, while in 

 A. plicatiira the anterior ribs are prettily nodulous. 



Area biiccida Conrad (Fos. Med. Tert., p. 60, pi. 31, fig. 4) appears to be 

 a short, heavy, stunted, and abnormally thickened variety of this species, 

 such as might be produced by an unfavorable environment. It is confined to 

 the Upper Miocene marls of Duplin County, North Carolina. 



Scapharca (Scapharca) plicatura Conrad. 

 Area plicatura Conrad, Fos. Med. Tert., p. 6.1, pi. 32, fig. 4, 1845 ; Heilprin, Proc. Acad. 



Nat. Sci. Phila. for 1881, p. 451, ex parte. 

 Area lineolata Conrad, Fos. Med. Tert., p. 61, pi. 32, fig. 3, 1845 ; not of Roemer, 1836. 

 A7'ca siiblitieolata Orbigny, Prodr. Pal., iii., p. 125. 

 Area CEquicostata Conrad, Fos. Med Tert., p. 60, pi. 31, fig. 6, 1845 ; Tuomey and 



Holmes (?), Pleioc. Fos. S. Car., p. 44, pi. 16, figs. 3, 4, 1856. 

 Area brevidesma Conrad, Fos. Med. Tert., p. 62, pi. 32, fig. 5, 1845. 



Upper Miocene of Duplin County, North Carolina, of the Sumter Dis- 

 trict, South Carolina, and of De Leon Springs, Florida ; Pliocene of the 

 Waccamaw beds of South Carolina ; Burns and Johnson. 



This is a considerably larger species than A. hnprocera, more rounded and 

 with a tendency to nodulatiou of the ribs. I am somewhat doubtful if the 

 shell figured by Tuomey and Holmes is to be identified with it. It has a very 

 close resemblance to A. arata Say, and is much larger than any specimens 

 of plicatiira I have seen. The sculpture of the two valves in plicatura is 

 markedly discrepant, which is not the case in improccra. In this, the former 

 more nearly approaches A. transversa, but the latter has reverted to the 

 rhombical form of improcera. 



Scapharca (Scapharca) campyla n. s. 

 Plate 31, Figures 3, 4; Plate 32, Figure 22. 

 Pliocene of the Caloosahatchie, Shell Creek, Alligator Creek, and Myakka 

 River, Florida ; Willcox and Dall. 



Shell of moderate size, solid, rather rude, the posterior end strongly 

 twisted to the right, the beaks low, and the form somewhat compressed ; the 



